Hydrocarbon oil treatment



Patented May 18, 1937 UNITED STATES HYDROCARBON OIL TREATMENT Seymour W. Ferris, Aldan, Pa., assignor to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Application March 25, 1933, Serial No. 662,840

18 Claims.

The present invention relates to the art of mineral oil refining, and has particular reference to the separation of crude petroleum or petroleum products into fractions of different chemical composition while of approximately the same distlllation range.

In accordance with my invention, crude petroleum or petroleum products, particularly oils of substantial viscosity, are separated into various fractions by means of fractional extraction with quinoline or its homologues, such as quinaldine; iso-quinoline; or a mixture of solvents containing substantial amounts of quinoline.

It is recognized in the art that mineral oils, such as petroleum, comprise essentially a mixture of hydrocarbons of various groups or homologous series of compounds, such for example, as paraflins of the general formula CnH21L+2, olefines of the general formula CnHZn, hydroaromatics and polymethylenes of the same empirical formula, and various other series of compounds of chain and/or ring structures in which the hydrogen to carbon ratio is less than in the foregoing series. A large number of individual compounds of each series and of differing boiling points are present in petroleum.

The various types of crude petroleum, which are generally classified into three groups, namely,

paraflinic base, naphthenic or asphaltic base, and

mixed base, contain the various series of hydrocarbons mentioned heretofore in different proportions. Forexample, in the parafiin base crude oils, such as those obtained from the oil fields of Pennsylvania, there is a relatively high proportion of hydrocarbons having a chain structure and a high hydrogen to carbon ratio, whereas in the naphthenic or asphaltic base crude oils, there is a relatively large proportion of hydrocarbons having ring structures and a low hydrogen to carbon ratio. Mixed base crude oils, such as are obtained from the Mid-Continent oil fields, contain hydrocarbons in proportions intermediate these two extremes.

The variance in the proportion of the different series of hydrocarbons in parafiinic, naphthenic, and mixed base oils is evidenced by the physical properties of the various oils and particularly by the relationship of the specific gravity to the viscosity of one oil as compared with another. For example, oils derived from a Pennsylvania crude and having a viscosity of400 seconds Saybolt universal at 100 F., will show a specific gravity at 60 F., of about 0.878, whereas an oil of corresponding viscosity produced from a naphthenic crude, such as one from the Gulf coast area, will show a specific gravity of about 0.933 at 60 F. The relationship between the viscosity and gravity indicates the degree of parafiinicity or vnaphthenicity of the .oil, and such relationship log (V-38),

G=0.24+0.755a+ 0.022 10g (.V35.5),

in which G is the specific gravity at 60 F., V and V are respectively Saybolt universal viscosities at 100 F. and 210 F., and a is a constant known as the viscosity-gravity constant. Viscous fractions from each of the different types of crude have difierent viscosity-gravity con-- stants. While, in general, Viscous fractions from a single crude have substantially the same viscosity-gravity constant, such constant is lower for fractions of the paraffinic crudes than is the constant for fractions of the naphthenic crudes. An article entitled The viscosity-gravity constant of petroleum lubricating oils by J. B. Hill and H. B. Coats, which will be found in volume 20', page 641 et sep., Industrial and Engineering Chemistry for June, 1928, explains the determination of such constant for several typical oils.

The viscosity-gravity constant is, therefore, an index of the paraflinicity or naphthenicity of viscous oils, since when a given crude is distilled, the fractions thereof collected, and the specific gravity and the viscosity of each of the viscous fractions determined, such specific gravities and viscosities substituted in the formula, and the viscosity-gravity constants of the fractions cal culated, it will be found that such constants are substantially the same.

The viscosity-gravity constants of the viscous fractions for some of the typical crudes are as follows:

Milltown (Pennsylvania) 0.8067 Burbank (Mid-Continent) 0.8367 Guadalupe (Gulf coast) 0.8635 Mirando (Gulf coast) 0.9025

While theabove figures indicate the viscositygravity constants of specific oils from several types of crudes, it is to be understood that for any particular type of crude such constant may be within a range between values above and below the constant of the typical crude given. For example, viscous oils resulting from the distillation of Mid-Continent crudes have viscositygravity constants ranging from about .835 to about .855, whereas the viscous fractions resulting from the distillation of Pennsylvania type crudes range from about ;805 to about .828, and

in most instances, are below .820. Oils are increasingly parafiiruc as their viscosity-gravity constants decrease.

My invention is based upon the discovery that oils containing both the paraffinic series of hydrocarbons and the various naphthenic series may be fractionally extracted with quinoline. The various series of hydrocarbons possess a differential solubility in such solvent, the naphthenic hydrocarbons being muchmore soluble therein than the paraffinic hydrocarbons. By means of extraction with such solvent, it is therefore possible to effect a partial separation of the naphthenic hydrocarbons from the paraffinic, and to obtain from an oil containing both classes of hydrocarbons, an oil which is much more paraffinic than the original oil and one which is much more naphthenic. By my invention, for example, it is possible to produce an oil of the quality normally obtained from Appalachlan crudes, from crudes of the mixed base type from the Mid -Continent area, and, conversely, to obtain oils from mixed base crudes such as are normally obtained from the naphthenic oils of the Gulf coast area. In general, from oils from any source there may be obtained by my process, oils which are respectively more paraflinic and more naphthenic than the oils normally obtained from such source by distillation.

In accordance with my invention, I first mix the oil to be treated with a suitable proportion of quinoline at a temperature such that complete solution is effected and a homogeneous liquid obtained. I then cool the mixture to a temperature at which separation of the liquid into a two-layer system will take place. The upper layer will contain a relatively small amount of the solvent dissolved in the parafllnic portion of the oil while the lower layer will contain the more naphthenic portion of the oil dissolved in the solvent. Or, I may agitate the mixture of solvent and oil at temperatures at which the liquids are only partially miscible, and thereby effect solution of the naphthenic portion of the oil in the solvent. In either of the above procedures I may take advantage of the principles of counter-current extraction.

After the extraction proper, I eiIect separation of the two layers which form, by any suitable procedure, as for example, by decantation. I then remove from each of the separated layers, the portion of solvent which each contains by suitable procedure, such as by vacuum distillation, thereby to obtain two oils of similar distillation ranges but of different chemical compositions and different physical characteristics.

Before removing the solvent from the upper and more parafiinic layer, I may add a further quantity of solvent and repeat the extraction, thereby to remove additional naphthenic constituents from said layer. The extraction step may be repeated any desired number of times, each repetition producing an oil of higher paraffinicity as evidenced by its lower viscosity-gravity constant.

Where substantial quantities of waxy hydrocarbons belonging to the true paraflin series (CnH2n+2) are present, such hydrocarbons remain in the upper or more paraffinic layer and may cause such layer to be solid or semi-solid. Such layer may be separated into solid and liquid hydrocarbons by any of the well-known dewaxing processes such as by cold-settling or by centrifuging. In many instances it may be advantageous to dewax the oil prior to extraction.

However, it is to be understood that in accordance with my invention, dewaxing may be effected either prior or subsequent to extraction.

My invention will be further understood from the following specific example:

parts of a Mid-Continent distillate having a viscosity of 305 seconds Saybolt universal at 100 F., a specific gravity of 0.9088 at 60 F., and a. viscosity-gravity constant of 0.853, was mixed with 300 parts of quinoline and heated to slightly above the temperature of complete miscibility, which was approximately 14 C. The homogeneous liquid which resulted was cooled with agitation to l0 0., and allowed to settle, whereupon a two layer system formed. After separation, the layers were each freed of solvent by vacuum distillation. The undissolved oil fraction comprising 46.2% of the stock had a vis cosity of 199 seconds Saybolt universal at 100 F., a specific gravity of 0.8729 and a viscosity-gravity constant 0.316. The dissolved oil fraction comprising 53.8% of the stock had a viscosity of 502 seconds Saybolt universal at 100 F., a specific gravity of 0.9408, and a viscosity-gravity constant of 0.893.

From the above example it will be noted that by extraction of an oil with quinoline, there may be obtained oil fractions which are respectively more parafiinic and more naphthenic than the original oil. By repetition of the extraction process upon the undissolved fraction, oils of even greater paraffinicity will result.

My process is practically independent of the particular nature or source of the crude oil or oil fraction to be extracted. There may be produced by my process oil products of desired characteristics from oils which by distillation will not produce such products.

Hereinabove, mixtures of solvents have been referred to. It is to be understood that in such mixtures the constituents will not react with one another nor with the oil upon which they are to be used, and that such mixtures will contain substantial amounts of quinoline.

Herein and in the appended claims, when oil is specifically referred to as being viscous, it is to be understood that the oil is of substantial viscosity, i. e., of the order of 50 seconds Saybolt uni' versal at 100 F., or more. Also, when in the appended claims the term quinoline is used, it is to be understood to comprehend quinoline its homologues, such as quinaldine iso-quinoline or mixtures of two or more of the same.

What I claim is:

1. In the art of refining mineral oils, the process the temperature at which the oil is substantially completely miscible with the quinoline.

2. In the art of refining mineral oils, the proc ess which comprises adding quinoline to an oil containing liquid paramnic and naphthenic hydrocarboris, heating the mixture to such temperature as to eirect Solution, cooling the solution toa temperature below the temperature at which the oil is substantially completely miscible with the quinoline to form a two-layer system the layers being respectively richer in parafiinic and naphthenic hydrocarbons, and separating the upper layer from the lower layer;

3, In the art of refiningmineral oils, the process which comprises adding quinoline to an oil containing liquid parafii nic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solution, cooling the solution to a temperature below the temperature at which the oil is substantially completely miscible with the quinoline to form a two layer system the layers being respectively richer in paraffinic and naphthenic hydrocarbons, removing the lower layer, and similarly retreating the upper layer with quinoline.

4. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing liquid paraflinic and naphthenic hydrocarbons into contact with quinoline, thereby to effect solution of a portion richer in naphthenic hydrocarbons in the quinoline, separating the solution so formed from the remainder of the oil at a temperature below the temperature at which the oil is substantially completely miscible with the quinoline, and removing the quinoline from both portions of the oil, thereby to obtain fractions of the oil respectively richer in liquid paraffinic and naphthenic hydrocarbons.

5. The process for separating mineral oils containing liquid paraifinic and naphthenic hydrocarbons into fractions which comprises bringing the oil into contact with quinoline, thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons in the quinoline, separating the solution so formed from the remainder of the oil at a temperature below the temperature at which the oil is substantially completely miscible with the quinoline, and distilling the quinoline from both of the portions of the oil, thereby to obtain fractions of the oil respectively richer in liquid paraifinic and naphthenic hydrocarbons.

6. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing liquid paraihnic and naphthenic hydrocarbons into contact with quinoline, thereby to efifect solution of a portion richer in naphthenic hydrocarbons in the solvent, separating the solution so formed from the remainder of the oil at a temperature below the temperature at which the oil is substantially completely miscible with the quinoline, and retreating the oil remaining with additional amounts of quinoline.

7. The method of producing paraffinic lubricating oil from mixed base crude which comprises distilling the crude and bringing a portion thereof into contact with quinoline, thereby partially dissolving the oil, separating the quinoline solution of oil so treated at a temperature below the temperature at which the oil is substantially completely miscible with the quinoline, and removing the quinoline from the treated oil thereby to effect separation of the oil into fractions respectively richer in paralilnic and naphthenic hydrocarbons.

8, In the art of refining mineral lubricating oil containing liquid paraffinic and naphthenic hydrocarbons, the stepof fractionally extracting the oil with quinoline, to effect a separation at a temperature below the temperature at which the oil is substantially completely miscible with the quinoline of fractions respectively richer in liquid parafiinic and naphthenic compounds.

9. The process of treating a viscous fraction of a crude oil of one type containing liquid paraffinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of difierent type having a greater content of liquid paraflinic hydrocarbons, which comprises extracting the viscous fraction with quinoline, and separating the oil 'so treated into portions respectively richer in liquid paraffinic and naphthenic hydrocarbons at a temperature below the temperature at which the oil is substantially completely miscible with the quinoline.

10. The process of treating a viscous fraction of a mixed base crude oil to procure a fraction having the quality of a corresponding fraction of a paraflim'c base crude, which comprises extracting the viscous fraction with quinoline, and separating the oil so treated into portions respectively richer in liquid paraffinic and naphthenic compounds at a temperature below the temperature at which the oil is substantially completely miscible with the quinoline.

11. In the art of refining mineral oils, the process which comprises adding quinoline to a viscous oil liquid at ordinary temperatures containing parafiinic and liquid naphthenic hydrocarbons, heating the mixture to a temperature a sufficient to effect solution, cooling the solution to a temperature below the temperature at which the oil is substantially completely miscible with the quinoline to form two layers respectively richer in naphthenic hydrocarbons and paraffinic hydrocarbons other than wax, and separating the upper layer richer in liquid paraflinic hydrocarbons from the lower layer richer in naphthenic hydrocarbons.

12. In the art of refining mineral oils, the process which comprises adding quinoline to a viscous oil liquid at ordinary temperatures containing liquid paraflinic and naphthenic hydrocarbons, heating the mixture to a temperature sufficient to effect solution, cooling the solution to a temperature below the temperature at which the oil is substantially completely miscible with the quinoline, to form two layers, and separating the quinoline from each layer, thereby to produce one fraction richer in liquid parafiinic and a second fraction richer in naphthenic hydrocarbons than said viscous oil.

13. In the art of refining mineral oils, the process which comprises bringing quinoline into intimate contact with a viscous hydrocarbon oil of a quality other than that of a Pennsylvania type viscous oil, and containing paraffinic and naphthenic components, thereby to dissolve from the oil substantial amounts of its naphthenic components, thereafter at a temperature below the temperature at which the oil is substantially completely miscible with the quinoline removing the solvent and oil dissolved therein from that portion of the oil which remains undissolved, thereby to produce an oil such as is normally obtained from Pennsylvania type crude by distillation.

14. The process of decreasing the viscositygravity constant of a viscous mineral oil which comprises extracting the oil with quinoline at a temperature below the temperature at which the oil is substantially completely miscible with the quinoline thereby to effect separation of the oil into fractions respectively richer in parafiinic and naphthenic hydrocarbons.

15. The process of decreasing the viscositygravity constant of a viscous mineral oil at least 0.015 which comprises extracting the oil with quinoline at a temperature below the temperature at which the oil is substantially completely miscible with the quinoline thereby to efiect separation of the oil into fractions respectively richer in paraflinic and naphthenic hydrocarbons.

16. The process of treating a viscous mineral oil of viscosity-gravity constant between substantially 0.850 and 0.875 to reduce the viscosity-gravity constant by at least 0.015, which comprises fractionally extracting said viscous oil with quinoline.

17. The process of treating a viscous mineral oil of viscosity-gravity constant higher than 0.850. to produce an oil having a viscosity-gravity con! stant less than 0.828 which comprises fractionally extracting said viscous oil With quinoline 18. The process of treating a viscous mineral oil of viscosity-gravity constant higher than 0.835 to produce an oil having a viscosity-gravity constant of less than 0.828 which comprises fractionally extracting said viscous oil with quinoline.

SEYMOUR W. FERRIS 

